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Wong" Cc: "Rafael J. Wysocki" , Linux PM , Linux Memory Management List , linux-fsdevel@vger.kernel.org, mkleinsoft@gmail.com, Christoph Hellwig , Andrew Morton , "Rafael J. Wysocki" , Len Brown , Pavel Machek Subject: [PATCH] hibernate: Allow uswsusp to write to swap Message-ID: <20200304082327.GA14236@dumbo> References: <20200229170825.GX8045@magnolia> <20200229180716.GA31323@dumbo> <20200229183820.GA8037@magnolia> <20200229200200.GA10970@dumbo> <20200303190212.GC8037@magnolia> <9E4A0457-39B1-45E2-AEA2-22C730BF2C4F@gmail.com> <20200304011840.GD1752567@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304011840.GD1752567@magnolia> User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Domenico Andreoli It turns out that there is one use case for programs being able to write to swap devices, and that is the userspace hibernation code. Quick fix: disable the S_SWAPFILE check if hibernation is configured. Fixes: 1638045c3677 ("mm: set S_SWAPFILE on blockdev swap devices") Reported-by: Domenico Andreoli Reported-by: Marian Klein Signed-off-by: Domenico Andreoli --- fs/block_dev.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) Index: b/fs/block_dev.c =================================================================== --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -2001,7 +2001,8 @@ ssize_t blkdev_write_iter(struct kiocb * if (bdev_read_only(I_BDEV(bd_inode))) return -EPERM; - if (IS_SWAPFILE(bd_inode)) + /* uswsusp needs to write to the swap */ + if (IS_SWAPFILE(bd_inode) && !IS_ENABLED(CONFIG_HIBERNATION)) return -ETXTBSY; if (!iov_iter_count(from))